Light-emitting device

ABSTRACT

A light-emitting device includes a first semiconductor layer; a semiconductor pillar formed on the first semiconductor layer, including a second semiconductor layer and an active layer, wherein the semiconductor pillar comprises an outmost periphery; a first contact layer formed on the first semiconductor layer and including a first contact portion and a first extending portion, wherein the first extending portion continuously surrounds an entirety of the outmost periphery of the semiconductor pillar and the first contact portion; a second contact layer formed on the second semiconductor layer; a first insulating layer including multiple first openings exposing the first contact layer and multiple second openings exposing the second contact layer; a first electrode contact layer connected to the first contact portion through the multiple first openings and covering all of the first contact layer; a second electrode contact layer connected to the second contact layer through the multiple second openings.

TECHNICAL FIELD

The application relates to a structure of a light-emitting device, andmore particularly, to a light-emitting device emitting an ultravioletlight, including a first semiconductor layer and a plurality ofsemiconductor pillars on the first semiconductor layer.

REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. Pat. ApplicationSerial No. 16/726,576, filed on Dec. 24, 2019, now pending, which is acontinuation application of U.S. Pat. Application Serial No. 16/035,299,filed on Jul. 13, 2018, now issued, which claims the right of prioritybased on TW Application Serial No. 106123445, filed on Jul. 13, 2017,the right of priority based on TW Application Serial No. 107123088,filed on Jul. 4, 2018, and the content of which are hereby incorporatedby references in its entirety.

DESCRIPTION OF BACKGROUND ART

Light-Emitting Diode (LED) is a solid-state semiconductor light-emittingdevice, which has the advantages of low power consumption, low heatgeneration, long working lifetime, shockproof, small volume, fastreaction speed and good photoelectric property, such as stable emissionwavelength. Therefore, light-emitting diodes are widely used inhousehold appliances, equipment indicators, and optoelectronic products.

SUMMARY OF THE APPLICATION

A light-emitting device includes a substrate; an aluminum nitride (AlN)buffer layer formed on the substrate; a first semiconductor layerincluding AlxGa(1-x)N formed on the aluminum nitride (AlN) buffer layer,wherein x>0; a semiconductor pillar formed on the first semiconductorlayer, including a second semiconductor layer and an active layer,wherein the semiconductor pillar includes an outmost periphery; a firstcontact layer formed on the first semiconductor layer, wherein the firstcontact layer includes a first contact portion and a first extendingportion, wherein the first extending portion continuously surrounds anentirety of the outmost periphery of the semiconductor pillar and thefirst contact portion in a top view of the light-emitting device; asecond contact layer formed on the second semiconductor layer of thesemiconductor pillar; a first insulating layer formed on the firstcontact layer and the second contact layer, wherein the first insulatinglayer includes one or multiple first openings exposing the first contactlayer and one or multiple second openings exposing the second contactlayer; a first electrode contact layer connected to the first contactportion through the one or multiple first openings of the firstinsulating layer, wherein the first electrode contact layer covers allof the first contact layer; a second electrode contact layer connectedto the second contact layer through the one or multiple second openingsof the first insulating layer; a second insulating layer formed on thefirst electrode contact layer and the second electrode contact layer,wherein the second insulating layer includes one or multiple firstopenings exposing the first electrode contact layer and one or multiplesecond openings exposing the second electrode contact layer; a firstelectrode formed on the second insulating layer, wherein the firstelectrode covers the one or multiple first openings of the secondinsulating layer and is in contact with the first electrode contactlayer to electrically connect the first semiconductor layer by the firstcontact portion; and a second electrode formed on the second insulatinglayer, wherein the second electrode covers the one or multiple secondopenings of the second insulating layer and is in contact with thesecond electrode contact layer to electrically connect the secondsemiconductor layer by the second contact layer.

A light-emitting device includes a substrate; an aluminum nitride (AlN)buffer layer formed on the substrate; a first semiconductor layerincluding AlxGa(1-x)N formed on the aluminum nitride (AlN) buffer layer,wherein x>0; a semiconductor pillar formed on the first semiconductorlayer, including a second semiconductor layer and an active layer,wherein the semiconductor pillar includes an outmost periphery; a firstcontact layer formed on the first semiconductor layer, wherein the firstcontact layer includes a first contact portion and a first extendingportion, wherein the first extending portion continuously surrounds anentirety of the outmost periphery of the semiconductor pillar and thefirst contact portion in a top view of the light-emitting device; asecond contact layer formed on the second semiconductor layer of thesemiconductor pillar; a first electrode contact layer connected to thefirst contact portion, wherein the first electrode contact layerincludes an outmost periphery; a second electrode contact layerconnected to the second contact layer, wherein the second electrodecontact layer surrounds an entirety of the outmost periphery of thefirst electrode contact layer in the top view of the light-emittingdevice; an insulating layer formed on the first electrode contact layerand the second electrode contact layer, wherein the insulating layerincludes one or multiple first openings formed on the first electrodecontact layer and one or multiple second openings formed on the secondelectrode contact layer; a first electrode formed on the insulatinglayer, wherein the first electrode covers the one or multiple firstopenings of the insulating layer and is electrically connected to thefirst electrode contact layer and the first semiconductor layer; and asecond electrode formed on the second insulating layer, wherein thesecond electrode covers the one or multiple second openings of theinsulating layer and is electrically connected to the second electrodecontact layer and the second semiconductor layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a top view of a light-emitting device 1 in accordancewith an embodiment of the present application;

FIG. 2 illustrates a cross-sectional view of the light-emitting device 1in accordance with an embodiment of the present application;

FIG. 3A illustrates a partial cross-sectional view of a light-emittingdevice 2A in accordance with an embodiment of the present application;

FIG. 3B illustrates a partial top view of the light-emitting device 2Ain accordance with an embodiment of the present application;

FIG. 4A illustrates a partial cross-sectional view of a light-emittingdevice 2B in accordance with an embodiment of the present application;

FIG. 4B illustrates a partial top view of the light-emitting device 2Bin accordance with an embodiment of the present application;

FIG. 5 illustrates a schematic view of a light-emitting apparatus 3 inaccordance with an embodiment of the present application; and

FIG. 6 illustrates a structure diagram of a light-emitting apparatus 4in accordance with an embodiment of the present application.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The embodiment of the application is illustrated in detail, and isplotted in the drawings. The same or the similar part is illustrated inthe drawings and the specification with the same number.

FIG. 1 illustrates a top view of a light-emitting device 1 in accordancewith an embodiment of the present application. FIG. 2 illustrates across-sectional view of FIG. 1 along line A-A′.

As shown in FIG. 1 and FIG. 2 , a light-emitting device 1 includes asubstrate 11; and a semiconductor stack formed on the substrate 11,wherein the semiconductor stack includes a first semiconductor layer111, and a plurality of semiconductor pillars 12 separated from eachother and formed on the first semiconductor layer 111. The plurality ofsemiconductor pillars 12 each includes a second semiconductor layer 122and an active layer 123. In an embodiment of the present application,the semiconductor pillar 12 includes a part of the first semiconductorlayer 111, and the active layer 123 is formed between the firstsemiconductor layer 111 and the second semiconductor layer 122.

In an embodiment of the present application, the substrate 11 can be agrowth substrate, including gallium arsenide (GaAs) wafer for growingaluminum gallium indium phosphide (AlGaInP), or sapphire (Al₂O₃) wafer,gallium nitride (GaN) wafer or silicon carbide (SiC) wafer for growinggallium nitride (GaN), indium gallium nitride (InGaN) or aluminumgallium nitride (AlGaN).

In an embodiment of the present application, a plurality ofsemiconductor layers including optical characteristics and consisting ofsemiconductor materials is formed on the substrate 11 by organic metalchemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydridevapor deposition (HVPE), physical vapor deposition (PVD), or ionplating, wherein physical vapor deposition (PVD) including sputtering orevaporation. The plurality of semiconductor layers is patterned bylithography and etching to remove portions of the semiconductor layersand to form the semiconductor stack including the first semiconductorlayer 111, and the plurality of semiconductor pillars 12 consisting ofthe active layer 123 and the second semiconductor layer 122. The firstsemiconductor layer 111 and the second semiconductor layer 122 can becladding layers, have different conductivity types, electricalproperties, polarities, or doping elements for providing electrons orholes. For example, the first semiconductor layer 111 is an n-typesemiconductor and the second semiconductor layer 122 is a p-typesemiconductor. The active layer 123 is formed between the firstsemiconductor layer 111 and the second semiconductor layer 122. Theelectrons and holes combine in the active layer 123 under a currentdriving to convert electric energy into light energy and then light isemitted from the active layer 123. The wavelength of the light emittedfrom the light-emitting device 1 is adjusted by changing the physicaland chemical composition of one or more layers in the semiconductorstack. The material of the semiconductor stack includes a group III-Vsemiconductor material, such as Al_(x)In_(y)Ga₍₁₋ _(x-y))N orAl_(x)In_(y)Ga_((1-x-y))P, wherein 0≤x, y≤1; (x+y)≤1. According to thematerial of the active layer 123, when the material of the semiconductorstack is AlInGaP series material, red light having a wavelength between610 nm and 650 nm or yellow light having a wavelength between 550 nm and570 nm can be emitted. When the material of the semiconductor stack isInGaN series material, blue or deep blue light having a wavelengthbetween 400 nm and 490 nm or green light having a wavelength between 490nm and 550 nm can be emitted. When the material of the semiconductorstack is AlGaN series material, UV light having a wavelength between 400nm and 250 nm can be emitted. The active layer 123 can be a singleheterostructure (SH), a double heterostructure (DH), a double-sidedouble heterostructure (DDH), or a multi-quantum well structure, MQW).The material of the active layer 123 can be i-type, p-type, or n-typesemiconductor.

In an embodiment of the present application, a buffer layer (not shown)is formed between the semiconductor stack and the substrate 11 toimprove the epitaxial quality of the semiconductor stack. In anembodiment, an aluminum nitride (AlN) layer can be used as the bufferlayer. In an embodiment, the method for forming aluminum nitride (AlN)is PVD, and the target is made of aluminum nitride. In anotherembodiment, a target made of aluminum which reacts in a nitrogen sourceenvironment with a PVD method is used to form aluminum nitride.

In an embodiment of the present application, the substrate 11 includes asapphire (Al₂O₃) substrate, and the first semiconductor layer 111includes an aluminum gallium nitride (AlGaN) layer. In order to reducethe epitaxial defects caused by the lattice difference between the AlGaNlayer and the sapphire substrate, the AlN layer is formed as a bufferlayer between the AlGaN layer and the sapphire substrate, wherein theAlN buffer layer includes a thickness greater than 300 nm, preferablygreater than 1000 nm, and even greater than 2500 nm to fill theepitaxial defects. The aluminum nitride (AlN) buffer layer includescarbon (C), hydrogen (H), and/or oxygen (O) including a dopingconcentration lower than 2E+17. The aluminum (Al) composition percentageof the aluminum nitride (AlN) buffer layer is greater than that ofaluminum gallium nitride (AlGaN) of the first semiconductor layer 111.

As shown in the top view of FIG. 1 and the cross-sectional view of FIG.2 taken along line A-A′ of FIG. 1 , after the plurality of semiconductorlayers is formed on the substrate 11, the plurality of semiconductorlayers is patterned by lithography and etching to remove portions of thesemiconductor layers and to form the semiconductor stack including thefirst semiconductor layer 111 and the plurality of semiconductor pillars12 separated from each other, wherein the plurality of semiconductorpillars 12 each includes the second semiconductor layer 122 and theactive layer 123.

In an embodiment of the present application, the semiconductor pillars12 are separated from each other to expose a surface S1 of the firstsemiconductor layer 111. The substrate 11 includes a first sidewall 11s, the first semiconductor layer 111 includes a second sidewall 111 s,and the plurality of semiconductor pillars 12 each includes a thirdsidewall 12 s. As shown in FIG. 2 , the first sidewall 11 s of thesubstrate 11 is aligned to the second sidewall 111 s of the firstsemiconductor layer 111. An inclined angle or a right angle is betweenthe third sidewall 12 s of the semiconductor pillar 12 and the surfaceS1 of the first semiconductor layer 111.

In an embodiment of the present application, the inclined angle betweenthe third sidewall 12 s of the semiconductor pillar 12 and the surfaceS1 of the first semiconductor layer 111 includes an angle between 10degrees and 80 degrees, preferably less than 60 degrees, and morepreferably less than 40 degrees.

In an embodiment of the present application, the first sidewall 11 s ofthe substrate 11 is separated from the second sidewall 111 s of thefirst semiconductor layer 111 by a distance to expose a surface S2 ofthe substrate 11. An obtuse angle or a right angle is between the secondsidewall 111 s of the first semiconductor layer 111 and the surface S2of the substrate 11.

In an embodiment of the present application, an inclined angle betweenthe second sidewall 111 s of the first semiconductor layer 111 and thesurface S2 of the substrate 11 includes an angle between 10 degrees and80 degrees, preferably less than 60 degrees, and more preferably lessthan 40 degrees. A height between the surface S1 of the firstsemiconductor layer 111 and the surface S2 of the substrate 11 isgreater than 4000 Å, preferably greater than 6000 Å, and more preferablygreater than 8000 Å.

In an embodiment of the present application, the surface S2 of thesubstrate 11 is a flat surface, wherein the flat surface includes aroughness (Root mean square roughness, Rq) less than 8 nm, preferablyless than 5 nm, and more preferably less than 2 nm.

In an embodiment of the present application, the surface S2 of thesubstrate 11 includes a patterned surface (not shown), wherein thepatterned surface includes a plurality of recesses extending from thesurface S2 of the substrate 11 toward the interior of the substrate 11or a plurality of protrusions extending from the surface S2 of thesubstrate 11 toward the surface S1 of the first semiconductor layer 111.From the top view of the light-emitting device 1, the plurality ofrecesses or the plurality of protrusions each includes a circle, anellipse, a rectangle, a polygon, or any other shape. From the top viewof the light-emitting device 1, the plurality of recesses or theplurality of protrusions each includes a bottom portion that is flushwith the surface S2 of the substrate 11, and a top portion that isopposite to the bottom portion. The top portion may be a flat surface ora point. The depth or the height between the top portion and the bottomportion is between 0.1 µm and 2 µm, preferably between 0.2 µm and 0.9µm, and more preferably between 0.5 µm and 0.7 µm. The bottom portionincludes a width or a diameter between 0.05 µm and 1 µm, preferablybetween 0.2 µm and 0.8 µm, and more preferably between 0.3 µm and 0.5µm.

In an embodiment of the present application, viewing from the top viewof the light-emitting device 1 shown in FIG. 1 , the semiconductorpillars 12 each includes a circle, an ellipse, a rectangle, a polygon,or any other shape.

In an embodiment of the present application, reducing the diameter orthe width of the semiconductor pillar 12 can reduce the forwardvoltage(Vf) of the light-emitting device 1. From the top view of thelight-emitting device 1, the semiconductor pillar 12 includes a diameteror a width greater than 4 µm and/or less than 80 µm, preferably lessthan 50 µm, and more preferably less than 20 µm.

In an embodiment of the present application, the semiconductor pillars12 are arranged in a plurality of columns, and the semiconductor pillars12 arranged in any two adjacent columns or every two adjacent columnscan be aligned with each other or staggered.

In an embodiment of the present application, the semiconductor pillars12 can be arranged in a first column and a second column. A firstshortest distance is between two adjacent semiconductor pillars 12 inthe same column, and a second shortest distance is between one of thesemiconductor pillars 12 in the first column and another adjacent one ofthe semiconductor pillars 12 in the second column, wherein the firstshortest distance is greater than or less than the second shortestdistance. When an external current is injected into the light-emittingdevice 1, the dispersed disposition of the plurality of semiconductorcolumns 12 uniforms the light field distribution of the light-emittingdevice 1 and reduces the forward voltage of the light-emitting device 1.

In an embodiment of the present application, the semiconductor pillars12 can be arranged in a first column, a second column and a thirdcolumn. A first shortest distance is between one of the semiconductorpillars 12 in the first column and another one of the semiconductorpillars 12 in the second column, and a second shortest distance isbetween one of the semiconductor pillars 12 in the second column andanother one of the semiconductor pillars 12 in the third column, whereinthe first shortest distance is less than the second shortest distance.When an external current is injected into the light-emitting device 1,the dispersed disposition of the plurality of semiconductor columns 12uniforms the light field distribution of the light-emitting device 1 andreduces the forward voltage of the light-emitting device 1.

A first contact layer 131 is formed on the surface S1 of the firstsemiconductor layer 111 by physical vapor deposition or chemical vapordeposition. The material of the first contact layer 131 includes metalmaterial, such as chromium (Cr), titanium (Ti), tungsten (W), gold (Au),aluminum (Al), indium (In), tin (Sn), nickel (Ni), platinum (Pt),rhodium (Rh), or an alloy of the above materials.

In an embodiment of the present application, the light emitted from thelight-emitting device 1 includes a wavelength longer than 370 nm, andthe material of the first contact layer 131 includes a metal having highreflectivity, such as silver (Ag), aluminum (Al), platinum (Pt) orrhodium (Rh). In order to increase the reflectivity of the first contactlayer 131, the metal layer of silver (Ag), aluminum (Al), platinum (Pt),or rhodium (Rh) includes a thickness greater than 400 angstroms (Å),preferably greater than 800 angstroms (Å), and more preferably greaterthan 1200 angstroms (Å).

In an embodiment of the present application, the light emitted from thelight-emitting device 1 includes a wavelength shorter than 370 nm, andthe material of the first contact layer 131 does not include silver(Ag).

In an embodiment of the present application, one side of the firstcontact layer 131 contacting with the surface S1 of the firstsemiconductor layer 111 includes chromium (Cr) or titanium (Ti) toincrease the bonding strength between the first contact layer 131 andthe first semiconductor layer 111. In order to reduce the light loss,the thickness of chromium (Cr) or titanium (Ti) layer is lower than 1000angstroms (Å), preferably lower than 600 angstroms (Å), and morepreferably lower than 400 angstroms (Å).And, in order to maintainsufficient bonding strength, chromium (Cr) and/or titanium (Ti) layersinclude a thickness greater than 10 angstroms (Å), preferably greaterthan 50 angstroms (Å), and more preferably greater than100 angstroms(Å).

In an embodiment of the present application, the first semiconductorlayer 111 includes Al_(x)Ga_((1-x))N, where 0.3<x<0.8, preferably0.35<x<0.7, and more preferably 0.4<x<0.6. In order to form an ohmiccontact between the first contact layer 131 and the surface S1 of thefirst semiconductor layer 111, and maintain a sufficient bondingstrength therebetween, the first contact layer 131 includes titanium(Ti) and aluminum (Al), wherein a ratio of a titanium (Ti) layer to analuminum (Al) layer is between 0.1 and 0.2.

In an embodiment of the present application, the first contact layer 131includes a first contact portion P1 and a first extending portion E1.The first contact portion P1 includes a projected area on the firstsemiconductor layer 111 that is larger than a projected area of one ofthe plurality of semiconductor pillars 12 on the first semiconductorlayer 111, wherein the projected area refers to a surface area along anormal direction perpendicular to the surface S2 of the substrate 11. Asshown in FIG. 1 , the first extending portion E1 extends from the firstcontact portion P1 and surrounds the plurality of semiconductor pillars12.

In an embodiment of the present application, the first contact layer 131includes a plurality of first contact portions P1 and a plurality offirst extending portions E1, wherein the plurality of first extendingportions E1 is extended from the plurality of first contact portions P1and are connected to each other, and the plurality of first contactportions P1 is electrically connected by the plurality of firstextending portions E1.

As shown in FIG. 2 , in an embodiment of the present application, thefirst contact portion P1 of the first contact layer 131 includes a widthlarger than a width of the first extending portion E1.

A second contact layer 132 is formed on the second semiconductor layer122 of the semiconductor pillar 12 by physical vapor deposition orchemical vapor deposition. The material of the second contact layer 132includes metal, such as chromium (Cr), titanium (Ti), tungsten (W), gold(Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni), platinum (Pt),rhodium (Rh), or an alloy of the above materials.

In an embodiment of the present application, the light emitted from thelight-emitting device 1 includes a wavelength longer than 370 nm, andthe material of the second contact layer 132 includes a metal havinghigh reflectivity, such as silver (Ag), aluminum (Al), platinum (Pt) orrhodium (Rh). In order to increase the reflectivity of the secondcontact layer 132, the metal layer of silver (Ag), aluminum (Al),platinum (Pt), or rhodium (Rh) includes a thickness greater than 400angstroms (Å), preferably greater than 800 angstroms (Å), and morepreferably greater than 1200 angstroms (Å).

In an embodiment of the present application, the light emitted from thelight-emitting device 1 includes a wavelength shorter than 370 nm, andthe material of the second contact layer 132 does not include silver(Ag).

In an embodiment of the present application, a plurality of secondcontact layers 132 are respectively formed on the second semiconductorlayer 122 of the plurality of semiconductor pillars 12, and theplurality of second contact layers 132 are separated from each other.

In an embodiment of the present application, the second semiconductorlayer 122 includes GaN, AlGaN or BN, and the second semiconductor layer122 includes a doping element such as magnesium (Mg) to form a p-typesemiconductor, wherein the doping element includes a concentrationgreater than 9E+18, preferably greater than 4E+19, and more preferablygreater than 1E+20. The second contact layer 132 includes a transparentconductive material that is transparent to the light emitted from theactive layer 123 and capable of forming ohmic contact with the secondsemiconductor layer 122. The transparent conductive material includes anon-metal material such as graphene, metal, or metal oxide such asindium tin oxide (ITO) or indium zinc oxide (IZO). The second contactlayer 132 is substantially formed on the entire surface of the secondsemiconductor layer 122 and contacts the second semiconductor layer 122.The electrical current is uniformly spread into the second semiconductorlayer 122 through the second contact layer 132.In an embodiment of thepresent application, the second contact layer 132 includes graphene, andthe second contact layer 132 further includes a thin metal layer or athin metal oxide layer with material such as nickel oxide (NiO), cobaltoxide (Co₃O₄), or copper oxide (Cu₂O) formed between the secondsemiconductor layer 122 and the graphene layer for forming ohmic contactwith the second semiconductor layer 122. The thin metal layer or thinmetal oxide layer includes a thickness between 0.1 and 100 nm,preferably between 0.1 and 50 nm, more preferably between 0.1 and 20nm.In an embodiment of the present application, the thickness of thesecond contact layer 132 is between 0.1 nm and 100 nm. If the thicknessof the second contact layer 132 is less than 0.1 nm, an ohmic contactwith the second semiconductor layer 122 cannot be formed therebetweenbecause the thickness is too thin. Besides, if the thickness of thesecond contact layer 132 is greater than 100 nm, the second contactlayer 132 is too thick to partially absorb light emitted from the activelayer 123, and the luminance of the light-emitting device 1 is reduced.

In an embodiment of the present application, The positions of the firstcontact layer 131 and the second contact layers 132 formed on thesemiconductor stack are misaligned and do not overlap each other.

A first insulating layer 14 is formed by physical vapor deposition orchemical vapor deposition to depositing an insulating material layer onthe first contact layer 131 and the second contact layer 132. The firstinsulating layer 14 is formed by patterning a portion of the insulatingmaterial layer by lithography and etching, and a first opening 1401 ofthe first insulating layer 14 is formed on the first contact layer 131to expose the first contact layer 131 and a second opening 1402 of thefirst insulating layer 14 is formed on the second contact layer 132 toexpose the second contact layer 132.

In an embodiment of the present application, the first contact layer 131includes the plurality of first contact portions P1 and the plurality offirst extending portions E1. The first insulating layer 14 includes aplurality of first openings 1401 respectively formed on the plurality offirst contacts P1, wherein the plurality of first extending portions E1is covered by the first insulating layer 14.

In an embodiment of the present application, the first insulating layer14 includes a plurality of second openings 1402 respectively formed onthe plurality of semiconductor pillars 12. In other words, an amount ofthe plurality of second openings 1402 is same as that of the pluralityof semiconductor pillars 12.

In an embodiment of the present application, an amount of the pluralityof second openings 1402 of the first insulating layer 14 is larger thanthat of the plurality of first openings 1401.

In an embodiment of the present application, the second opening 1402 ofthe first insulating layer 14 includes a width smaller than that of thefirst opening 1401.

In an embodiment of the present application, the first insulating layer14 covers the third sidewalls 12 s of the plurality of semiconductorpillars 12, covers the surface S1 of the first semiconductor layer 111,covers the second sidewall 111 s of the first semiconductor layer 111,and/or covers the surface S2 of the substrate 11.

In an embodiment of the present application, the first insulating layer14 protects the semiconductor structure, and includes two or more layershaving different refractive indexes alternately stacked to form aDistributed Bragg reflector (DBR). The DBR selectively reflects light ofa specific wavelength. The first insulating layer 14 is formed of anon-conductive material including organic material, inorganic materialor dielectric material. The organic material includes Su8,benzocyclobutene (BCB), perfluorocyclobutane (PFCB), epoxy resin,acrylic resin, cyclic olefin polymers (COC), polymethylmethacrylate(PMMA), polyethylene terephthalate (PET), polycarbonate (PC),polyetherimide, or fluorocarbon polymer. The inorganic material includessilicone or glass. The dielectric material includes aluminum oxide(Al₂O₃), silicon nitride (SiN_(x)), silicon oxide (SiO_(x)), titaniumoxide (TiO_(x)), or magnesium fluoride (MgF_(x)).

A first electrode contact layer 151 and a second electrode contact layer152 are respectively formed in the first opening 1401 and the secondopening 1402 of the first insulating layer 14 by physical vapordeposition or chemical vapor deposition, and extend and cover portionsof the surface of the first insulating layer 14. The first electrodecontact layer 151 is connected to the first contact portion P1 of thefirst contact layer 131 through the first opening 1401 of the firstinsulating layer 14. The second electrode contact layer 152 is connectedto the plurality of second contact layers 132 through the second opening1402 of the first insulating layer 14.

In an embodiment of the present application, the second electrodecontact layer 152 covers the plurality of semiconductor pillars 12 andportions of the first contact layer 131, wherein the second electrodecontact layer 152 is electrically isolated from the first contact layer131 by the first insulating layer 14.

In an embodiment of the present application, the first contact layer 131includes the first contact portion P1 including a width W1 larger than awidth W2 of the semiconductor pillar 12, the width W1 of the firstcontact portion P1 of the first contact layer 131 is larger than thewidth W3 of the first electrode contact layer 151, and the width W3 ofthe first electrode contact layer 151 is larger than the width W2 of thesemiconductor pillar 12.

In an embodiment of the present application, the first electrode contactlayer 151 covers portions of the first contact layer 131, the secondelectrode contact layer 152 covers all of the second contact layers 132.

In an embodiment of the present application, the first electrode contactlayer 151 covers portions of the first contact layer 131, the secondelectrode contact layer 152 covers portions of the second contact layers132.

In an embodiment of the present application, the first electrode contactlayer 151 covers all of the first contact layer 131, the secondelectrode contact layer 152 covers portions of the second contact layers132.

In an embodiment of the present application, the first electrode contactlayer 151 and the second electrode contact layer 152 are separated fromeach other by a distance. In the top view of the light-emitting device1, the second electrode contact layer 152 surrounds multiple sidewallsof the first electrode contact layer 151.

In an embodiment of the present application, in the top view of thelight-emitting device 1, the second electrode contact layer 152 includesan area larger than an area of the first electrode contact layer 151.

In an embodiment of the present application, when an external current isinjected into the light-emitting device 1, the electrical current isconducted to the first semiconductor layer 111 and the secondsemiconductor layer 122 by the first electrode contact layer 151 and thesecond electrode contact layer 152.

As shown in FIG. 1 , the first electrode contact layer 151 is close toone side of the substrate 11, such as the left or right side of acenterline of the substrate 11.

In an embodiment of the present application, the material of the firstelectrode contact layer 151 and the second electrode contact layer 152include a metal material, such as chromium (Cr), titanium (Ti), tungsten(W), gold (Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni),platinum (Pt), rhodium (Rh), or an alloy of the above materials.

In an embodiment of the present application, the light emitted from thelight-emitting device 1 includes a wavelength shorter than 370 nm, andthe material of the first electrode contact layer 151 and the secondelectrode contact layer 152 do not include silver (Ag). The material ofthe first electrode contact layer 151 and the second electrode contactlayer 152 includes a metal having a high reflectivity for the UV light,such as aluminum (Al), platinum (Pt) or rhodium (Rh). In order toincrease the reflectivity of the first electrode contact layer 151 andthe second electrode contact layer 152 for the UV light, the layerincluding aluminum (Al), platinum (Pt), or rhodium (Rh) includes athickness greater than 4000 angstroms (Å), preferably greater than 8000angstroms (Å), and more preferably greater than 10000 angstroms (Å).

In an embodiment of the present application, one side of the firstelectrode contact layer 151 contacting with the first contact layer 131includes chromium (Cr) or titanium (Ti) to increase the bonding strengthbetween the first electrode contact layer 151 and the first contactlayer 131. The second electrode contact layer 152 contacting with thesecond contact layer 132 includes chromium (Cr) or titanium (Ti) toincrease the bonding strength between the second electrode contact layer152 and the second contact layer 132. In order to reduce the brightnessloss caused by the ultraviolet light of chromium (Cr) or titanium (Ti)material, a thickness of the layer including chromium (Cr) or titanium(Ti) material is lower than 1000 angstroms (Å), preferably lower than800 angstroms (Å), and more preferably lower than 500 angstroms (Å).And,in order to maintain sufficient bonding strength, the layer includingchromium (Cr) and/or titanium (Ti) includes a thickness greater than 10angstroms (Å), preferably greater than 50 angstroms (Å), and morepreferably greater than 100 angstroms (Å).

A second insulating layer 16 is formed by physical vapor deposition orchemical vapor deposition to deposit an insulating material layer on thefirst electrode contact layer 151 and the second electrode contact layer152. Then, the insulating material layer is patterned by lithography andetching to form the second insulating layer 16, and the first opening1601 and the second opening 1602 of the second insulating layer 16respectively exposing the first electrode contact layer 151 and thesecond electrode contact layer 152.

In an embodiment of the present application, the second insulating layer16 includes one or a plurality of first openings 1601 and one or aplurality of second openings 1602, wherein an amount of the plurality offirst openings 1601 and an amount of the plurality of second openings1602 are the same or different.

In an embodiment of the present application, the plurality of firstopenings 1601 of the second insulating layer 16 are respectively formedon the plurality of first electrode contact layers 151, wherein anamount of the plurality of first openings 1601 and an amount of theplurality of first electrode contact layers 151 are the same.

In the top view of FIG. 1 , the first opening 1601 and the secondopening 1602 of the second insulating layer 16 are respectively formedon two sides of the centerline of the substrate 11. For example, thefirst opening 1601 of the second insulating layer 16 is formed on theright side of the centerline of the substrate 11, and the second opening1602 of the second insulating layer 16 is formed on the left side of thecenterline of the substrate 11.

In an embodiment of the present application, the first opening 1601 ofthe second insulating layer 16 includes a width smaller than a width ofthe first opening 1401 of the first insulating layer 14.

In an embodiment of the present application, the first opening 1601 ofthe second insulating layer 16 overlaps the first opening 1401 of thefirst insulating layer 14, and the first opening 1601 of the secondinsulating layer 16 and the first opening 1401 of the first insulatinglayer 14 are both formed on the first contact layer 131.

In an embodiment of the present application, the second opening 1602 ofthe second insulating layer 16 and the second opening 1402 of the firstinsulating layer 14 are misaligned. Specifically, the second opening1402 of the first insulating layer 14 is formed on the second contactlayer 132, and the second opening 1602 of the second insulating layer 16is formed on the first contact layer 131.

In an embodiment of the present application, when the second insulatinglayer 16 includes a stack structure, and the stack structure includestwo or more sublayers; wherein the sublayers have two materials withdifferent refractive indexes alternately stacked to form a DistributedBragg reflector (DBR). The DBR selectively reflects light of a specificwavelength. The second insulating layer 16 is formed of a non-conductivematerial including organic material, inorganic material or dielectricmaterial. The organic material includes Su8, benzocyclobutene (BCB),perfluorocyclobutane (PFCB), epoxy resin, acrylic resin, cyclic olefinpolymers (COC), polymethylmethacrylate (PMMA), polyethyleneterephthalate (PET), polycarbonate (PC), polyetherimide, or fluorocarbonpolymer. The inorganic material includes silicone or glass. Thedielectric material includes aluminum oxide (Al₂O₃), silicon nitride(SiN_(x)), silicon oxide (SiO_(x)), titanium oxide (TiO_(x)), ormagnesium fluoride (MgF_(x)).

A first electrode 171 and a second electrode 172 are formed on thesecond insulating layer 16 by electroplating, physical vapor depositionor chemical vapor deposition. In the top view of FIG. 1 , the firstelectrode 171 is close to one side of the substrate 11, such as theright side of the centerline of the substrate 11, and the secondelectrode 172 is close to the other side of the substrate 11, such asthe left side of the centerline of the substrate 11. The first electrode171 covers the first opening 1601 of the second insulating layer 16 tobe in contact with the first electrode contact layer 151, and iselectrically connected with the first semiconductor layer 111 by thefirst contact layer 131. The second electrode 172 covers the secondopening 1602 of the second insulating layer 16 to be in contact with thesecond electrode contact layer 152, and is electrically connected withthe second semiconductor layer 122 by the second contact layer 132.

In an embodiment of the present application, the plurality ofsemiconductor pillars 12 formed under a covering area of the firstelectrode 171 includes a first space D1 to separate from each other. Theplurality of semiconductor pillars 12 outside the covering area of thefirst electrode 171 includes a second space D2 to separate from eachother, and the first spacing D1 is greater than the second spacing D2.

In an embodiment of the present application, the light emitting device 1further includes a semiconductor mesa. The semiconductor mesa includes afirst semiconductor layer, an active layer and a second semiconductorlayer, and is formed under the first electrode 171, wherein theplurality of semiconductor pillars 12 formed outside the covering areaof the first electrode 171 includes a second space D2 to separate fromeach other, and the second semiconductor layer of the semiconductor mesaincludes a width larger than the second space D2 between the pluralityof semiconductor pillars 12.

In an embodiment of the present application, the first contact portionP1 of the first contact layer 131 is formed under the first electrode171 and/or the second electrode 172. The first extending portion E1 ofthe first contact layer 131 is formed under the first electrode 171 andthe second electrode 172.

In an embodiment of the present application, the first electrode 171includes a size equal to or different from a size of the secondelectrodes 172. The size includes width or area.

In an embodiment of the present application, in the top view of thelight-emitting device 1, the shape of the first electrode 171 is thesame as or similar to that of the second electrode 172, for example, theshapes of the first electrode 171 and the second electrode 172 arerectangular, as shown in FIG. 1 .

In an embodiment of the present application, the first electrode 171 andthe second electrode 172 include metal materials, such as chromium (Cr),titanium (Ti), tungsten (W), aluminum (Al), indium (In), tin (Sn),nickel (Ni), platinum (Pt) or an alloy of the above materials. The firstelectrode 171 and the second electrode 172 include a single layer ormultiple layers. When the first electrode 171 and the second electrode172 include multiple layers, the first electrode 171 includes a firstupper pad and a first lower pad, and the second electrode 172 includes asecond upper pad and a second lower pad. The upper pads and the lowerpads have different functions.

In an embodiment of the present application, the function of the upperpad is mainly used for soldering and wire bonding. With the upper pad,the light-emitting device 1 can be mounted on a package substrate in aflip-chip form using solder or eutectic bonding, for example, an AuSnbonding. The metal material of the upper pad includes high-ductilitymaterial, such as tin (Sn), nickel (Ni), cobalt (Co), iron (Fe),titanium (Ti), copper (Cu), gold (Au), tungsten (W), zirconium (Zr),molybdenum (Mo), tantalum (Ta), aluminum (Al), silver (Ag), platinum(Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru) osmium(Os), or alloys thereof. The upper pad can be a single layer or alaminated structure of the above materials. In an embodiment of thepresent application, the material of the upper pad includes nickel (Ni)and/or gold (Au), and the upper pad is a single layer or a laminatedstructure

In an embodiment of the present application, the function of the lowerpad is to form a stable interface with the first electrode contact layer151 and the second electrode contact layer 152, for example, to increasethe interface bonding strength between the first lower pad and the firstelectrode contact layer 151, or to increase the interface bondingstrength between the second lower pad and the second electrode contactlayer 152. Another function of the lower pad is to prevent tin (Sn) inthe solder or AuSn eutectic from diffusing into the reflective structurethat destroys the reflectivity of the reflective structure. Therefore,the lower pad includes metal materials other than gold (Au), copper(Cu), such as nickel (Ni), cobalt (Co), iron (Fe), titanium (Ti),tungsten (W), zirconium (Zr). molybdenum (Mo), tantalum (Ta), aluminum(Al), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium(Ir), ruthenium (Ru), osmium (Os) or an alloy of the above materials.The lower pad can be a single layer or a laminated structure of theabove materials. In an embodiment of the present application, the lowerpad includes a laminated structure of titanium (Ti)/aluminum (Al) or alaminated structure of chromium (Cr)/aluminum (Al).

In an embodiment of the present application, in order to prevent tin(Sn) in the solder or AuSn eutectic from diffusing into the reflectivestructure that destroys the reflectivity of the reflective structure,one side of the first electrode contact layer 151 contacting with thefirst electrode 171 includes a metal material selected from the groupconsisting of titanium (Ti) and platinum (Pt). One side of the secondelectrode contact layer 152 contacting with the second electrode 172includes a metal material selected from the group consisting of titanium(Ti) and platinum (Pt).

FIG. 3A illustrates a partial cross-sectional view of a light-emittingdevice 2A in accordance with an embodiment of the present application.FIG. 3B illustrates a partial top view of the light-emitting device 2Ain accordance with an embodiment of the present application. Since thelight-emitting device 2A and the light-emitting device 1 havesubstantially the same structure, the descriptions about the samestructure of the light-emitting device 2A and the light-emitting device1 will be appropriately omitted or will not be repeated.

As shown in FIG. 3A and FIG. 3B, the light-emitting device 2Aillustrates another example of the structural embodiment of thesemiconductor pillar 12 of the light-emitting device 1 illustrated inFIG. 1 . In an embodiment of the present application, the semiconductorstack includes a first semiconductor layer 221, an active layer 223, anda semiconductor pillar 22 on the active layer 223. The active layer 223includes one or more well layers and one or more barrier layeralternatively stacked, wherein the well layer includes Al_(x)Ga_(1-x)Nand 0.2<x<0.4, and the barrier layer includes Al_(y)Ga_(1-y)N and0.4<y<0.7. The semiconductor pillar 12 shown in the light-emittingdevice 1 of FIG. 2 can be replaced by the semiconductor pillar 22 shownin FIGS. 3A and 3B, the semiconductor pillar 22 includes a secondsemiconductor layer 222. In an embodiment of the present application,the semiconductor pillar 22 further includes a portion of the activelayer 223. The active layer 223 is formed between the firstsemiconductor layer 221 and the second semiconductor layer 222, and theactive layer 223 emits a UV light.

In an embodiment of the present application, the substrate 11 includes afirst sidewall 11 s, the first semiconductor layer 221 includes a secondsidewall 221 s, the second semiconductor layer 222 includes a thirdsidewall 222 s, and the active layer 223 includes a sidewall 223 s. Asshown in FIG. 3A, the third sidewall 222 s of the second semiconductorlayer 222 is separated from the sidewall 223 s of the active layer 223by a distance to expose a surface S3 of the active layer 223, whereinthe exposed surface S3 of the active layer 223 can be the well layer orthe barrier layer, the well layer includes Al_(x)Ga_(1-x)N and 0.2<x<0.4, and the barrier layer includes Al_(y)Ga_(1-y)N and 0.4<y<0.7. Anobtuse angle or a right angle is between the third sidewall 222 s of thesecond semiconductor layer 222 and the surfaces S3 of the active layer223.

In an embodiment of the present application, in the top view of thelight-emitting device 2A shown in FIG. 3B, the second semiconductorlayer 222 each includes a circle, an ellipse, a rectangle, a polygon, orany other shape. The second semiconductor layer 222 is surrounded by theactive layer 223, and part of the surface S3 of the active layer 223 isexposed to be formed outside the covering area of the secondsemiconductor layer 222. Part of the surface S3 of the active layer 223is not covered by the second semiconductor layer 222, wherein theexposed surface S3 of the active layer 223 can be the well layer or thebarrier layer, the well layer includes Al_(x)Ga_(1-x)N and 0.2<x<0.4 ,and the barrier layer includes Al_(y)Ga_(1-y)N and 0.4<y<0.7.

In an embodiment of the present application, the active layer 223 issurrounded by the first semiconductor layer 221, and part of the surfaceS1 of the first semiconductor layer 221 is exposed to be formed outsidethe covering area of the active layer 223, wherein the firstsemiconductor layer 221 includes AlGaN. The part of the surface S1 ofthe first semiconductor layer 221 is not covered by the active layer223.

FIG. 4A illustrates a partial cross-sectional view of a light-emittingdevice 2B in accordance with an embodiment of the present application.FIG. 4B illustrates a partial top view of the light-emitting device 2Bin accordance with an embodiment of the present application. Since thelight-emitting device 2B and the light-emitting device 1 havesubstantially the same structure, the descriptions about the samestructure of the light-emitting device 2B and the light-emitting device1 will be appropriately omitted or will not be repeated.

As shown in FIG. 4A and FIG. 4B, the light-emitting device 2Billustrates another example of the structural embodiment of thesemiconductor pillar 12 of the light-emitting device 1 illustrated inFIG. 2 . In an embodiment of the present application, the semiconductorstack includes a first semiconductor layer 321, an active layer 323, anda plurality of semiconductor pillars 32 on the first semiconductor layer321. The semiconductor pillars 32 each includes a second semiconductorlayer 322, and the active layer 323 emits a UV light.

In an embodiment of the present application, the semiconductor pillar 32further includes part of the active layer 323. The active layer 323 isformed between the first semiconductor layer 321 and the secondsemiconductor layer 322, and the active layer 323 emits UV light.

In an embodiment of the present application, in the top view of thelight-emitting device 2B shown in FIG. 4B, the second semiconductorlayer 322 each includes a circle, an ellipse, a rectangle, a polygon, orany other shape. The second semiconductor layer 322 is surrounded by theactive layer 323, and part of the surface S3 of the active layer 323 isexposed to be formed outside the covering area of the secondsemiconductor layer 322. The part of the surface S3 of the active layer323 is not covered by the second semiconductor layer 323. The activelayer 323 is surrounded by the first semiconductor layer 321, and partof the surface S1 of the first semiconductor layer 321 is exposedoutside the coverage area of the active layer 323. The part of thesurface S1 of the first semiconductor layer 321 is not covered by theactive layer 323, wherein the first semiconductor layer 321 includesAlGaN.

FIG. 5 is a schematic view of a light-emitting apparatus 3 in accordancewith an embodiment of the present application. The light-emitting device1, 2A, or 2B in the foregoing embodiment is mounted on the first spacer511 and the second spacer 512 of the package substrate 51 in the form offlip chip. The first spacer 511 and the second spacer 512 areelectrically insulated from each other by an insulating portion 53including an insulating material. The main light-extraction surface ofthe flip chip is one side of the growth substrate 11 opposite to theelectrode-forming surface where the electrodes are formed on. Areflective structure 54 can be provided around the light-emitting device1, 2A, or 2B to increase the light extraction efficiency of thelight-emitting apparatus 3.

FIG. 6 illustrates a structure diagram of a light-emitting apparatus 4in accordance with an embodiment of the present application. A lightbulb includes an envelope 602, a lens 604, a light-emitting module 610,a base 612, a heat sink 614, a connector 616 and an electricalconnecting device 618. The light-emitting module 610 includes a submount606 and a plurality of light-emitting devices 608 on the submount 606,wherein the plurality of light-emitting devices 608 can be thelight-emitting device 1, 2A, or 2B or the light-emitting apparatus 3described in above embodiments.

The principle and the efficiency of the present application illustratedby the embodiments above are not the limitation of the application. Anyperson having ordinary skill in the art can modify or change theaforementioned embodiments. Therefore, the protection range of therights in the application will be listed as the following claims.

1-30. (canceled)
 31. A light-emitting device, comprising: a substrate;an aluminum nitride (A1N) buffer layer formed on the substrate; a firstsemiconductor layer comprising Al_(x)Ga_((1-x))N formed on the aluminumnitride (A1N) buffer layer, wherein x>0; a semiconductor pillar formedon the first semiconductor layer, comprising a second semiconductorlayer and an active layer, wherein the semiconductor pillar comprises anoutmost periphery; a first contact layer formed on the firstsemiconductor layer, wherein the first contact layer comprises a firstcontact portion and a first extending portion, wherein the firstextending portion continuously surrounds an entirety of the outmostperiphery of the semiconductor pillar and the first contact portion in atop view of the light-emitting device; a second contact layer formed onthe second semiconductor layer of the semiconductor pillar; a firstinsulating layer formed on the first contact layer and the secondcontact layer, wherein the first insulating layer comprises one ormultiple first openings exposing the first contact layer and one ormultiple second openings exposing the second contact layer; a firstelectrode contact layer connected to the first contact portion throughthe one or multiple first openings of the first insulating layer,wherein the first electrode contact layer covers all of the firstcontact layer; a second electrode contact layer connected to the secondcontact layer through the one or multiple second openings of the firstinsulating layer; a second insulating layer formed on the firstelectrode contact layer and the second electrode contact layer, whereinthe second insulating layer comprises one or multiple first openingsexposing the first electrode contact layer and one or multiple secondopenings exposing the second electrode contact layer; a first electrodeformed on the second insulating layer, wherein the first electrodecovers the one or multiple first openings of the second insulating layerand is in contact with the first electrode contact layer to electricallyconnect the first semiconductor layer by the first contact portion; anda second electrode formed on the second insulating layer, wherein thesecond electrode covers the one or multiple second openings of thesecond insulating layer and is in contact with the second electrodecontact layer to electrically connect the second semiconductor layer bythe second contact layer.
 32. The light-emitting device according toclaim 31, wherein 0.35<x<0.7.
 33. The light-emitting device according toclaim 32, wherein the first contact layer is directly in contact withthe first semiconductor layer.
 34. The light-emitting device accordingto claim 31, wherein the first semiconductor layer is formed on a flatsurface of the substrate.
 35. The light-emitting device according toclaim 31, wherein the first contact portion comprises a width largerthan a width of the first extending portion.
 36. The light-emittingdevice according to claim 31, wherein the first contact layer is coveredby the first electrode and the second electrode.
 37. The light-emittingdevice according to claim 31, wherein the aluminum nitride (A1N) bufferlayer comprises a thickness greater than 2500 nm.
 38. The light-emittingdevice according to claim 33, wherein the first contact layer comprisesone side comprising a chromium (Cr) layer to be in contact with thefirst semiconductor layer.
 39. The light-emitting device according toclaim 38, wherein a thickness of the chromium (Cr) layer is greater than10 angstroms and lower than 400 angstroms.
 40. The light-emitting deviceaccording to claim 31, wherein the second contact layer comprises ametal oxide layer, and a thickness of the metal oxide layer between 0.1and 20 nm.
 41. The light-emitting device according to claim 31, whereinthe active layer comprises one or more well layers and one or morebarrier layers alternatively stacked, wherein the barrier layercomprises Al_(y)Ga_(1-y)N and 0.4<y<0.7.
 42. The light-emitting deviceaccording to claim 31, wherein an UV light comprising a wavelengthshorter than 370 nm is emitted from the light-emitting device.
 43. Thelight-emitting device according to claim 42, wherein the first contactlayer does not comprise silver (Ag).
 44. The light-emitting deviceaccording to claim 42, wherein the first electrode contact layer and thesecond electrode contact layer do not include silver (Ag).
 45. Thelight-emitting device according to claim 31, wherein an amount of theone or multiple second openings of the first insulating layer is largerthan that of the one or multiple first openings of the first insulatinglayer.
 46. The light-emitting device according to claim 31, wherein awidth of the one or multiple the second opening of the first insulatinglayer is smaller than that of the one or multiple first openings of thefirst insulating layer.
 47. The light-emitting device according to claim31, wherein an amount of the one or multiple first openings of thesecond insulating layer and an amount of the one or multiple of secondopenings of the second insulating layer are different.
 48. Thelight-emitting device according to claim 31, wherein a width of the oneor multiple first opening of the second insulating layer is smaller thanthat of the one or multiple first opening of the first insulating layer.49. The light-emitting device according to claim 31, wherein the firstcontact layer comprises an outmost periphery, and an entirety of thefirst electrode and an entirety of the second electrode are locatedwithin the outmost periphery of the first contact layer in the top viewof the light-emitting device.
 50. A light-emitting device, comprising: asubstrate; an aluminum nitride (A1N) buffer layer formed on thesubstrate; a first semiconductor layer comprising Al_(x)Ga₍₁-_(x))Nformed on the aluminum nitride (A1N) buffer layer, wherein x>0; asemiconductor pillar formed on the first semiconductor layer, comprisinga second semiconductor layer and an active layer, wherein thesemiconductor pillar comprises an outmost periphery; a first contactlayer formed on the first semiconductor layer, wherein the first contactlayer comprises a first contact portion and a first extending portion,wherein the first extending portion continuously surrounds an entiretyof the outmost periphery of the semiconductor pillar and the firstcontact portion in a top view of the light-emitting device; a secondcontact layer formed on the second semiconductor layer of thesemiconductor pillar; a first electrode contact layer connected to thefirst contact portion, wherein the first electrode contact layercomprises an outmost periphery; a second electrode contact layerconnected to the second contact layer, wherein the second electrodecontact layer surrounds an entirety of the outmost periphery of thefirst electrode contact layer in the top view of the light-emittingdevice; an insulating layer formed on the first electrode contact layerand the second electrode contact layer, wherein the insulating layercomprises one or multiple first openings formed on the first electrodecontact layer and one or multiple second openings formed on the secondelectrode contact layer; a first electrode formed on the insulatinglayer, wherein the first electrode covers the one or multiple firstopenings of the insulating layer and is electrically connected to thefirst electrode contact layer and the first semiconductor layer; and asecond electrode formed on the second insulating layer, wherein thesecond electrode covers the one or multiple second openings of theinsulating layer and is electrically connected to the second electrodecontact layer and the second semiconductor layer.